Could you please send us a link where we can see this form issue?
As for the header, so you just need to create a clone of this header and enable “Header overlap” option. Then, edit this header in the Dashboard -> Pages and specify the newly created header for it https://gyazo.com/ff5cd3f83a83408f5166f54fb20e7e48
We found the contact form on your site by itself. In this situation, you can add more negative margins for parent row of your popup window via WPbakery display setting. Please check this video https://gyazo.com/437b115995a0eb53c19b6170799760c9.
Where i can find the icons you use in toy demo page???
and after i make the changes i dont know wht but the fonts dont look good https://prnt.sc/itgm5f
You can find and download all SVG icons used for our demo on this service flaticon.com
As for the font, you are able to change it in Theme Settings -> Typography.